Laboratory tests and outcome for patients with COVID-19: A systematic review and meta-analysis.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (COVID-19) poses substantial challenges for health care systems. With a vastly expanding amount of publications on COVID-19, clinicians need evidence synthesis to produce guidance for handling patients with COVID-19. In this systematic review and meta-analysis, we examine which routine laboratory tests are associated with severe COVID-19 disease. CONTENT: PubMed (Medline), Scopus, and Web of Science were searched until the 22nd of March 2020 for studies on COVID-19. Eligible studies were original articles reporting on laboratory tests and outcome of patients with COVID-19. Data were synthesised and we conducted random effects meta-analysis and estimated mean difference (MD) and standard mean difference at biomarker level for disease severity. Risk of bias and applicability concern was evaluated using the Quality Assessment of Diagnostic Accuracy Studies -2. SUMMARY: 45 studies were included, of which 21 publications were used for the meta-analysis. Studies were heterogeneous, but had low risk of bias and applicability concern in terms of patient selection and reference standard. Severe disease was associated with higher white blood cell count (MD 1.28 x 109/L), neutrophil count (MD 1.49 x 109/L), C-reactive protein (MD 49.2 mg/L), lactate dehydrogenase (MD 196 U/L), D-dimer (SMD 0.58), and aspartate aminotransferase (MD 8.5 U/L), all p < 0.001. Furthermore, low lymphocyte count (MD -0.32 x 109/L), platelet count (MD -22.4 x 109/L), and haemoglobin (MD -4.1 g/L), all p < 0.001, were also associated with severe disease. In conclusion, several routine laboratory tests are associated with disease severity in COVID-19.